1. Technical Field of the Invention
This invention relates to a substrate processing apparatus for cleaning a substrate, for example, semiconductor wafer, glass for LCD substrate, etc.
2. Description of the Related Art
For example, in the manufacturing process of semiconductor devices, there is employed a substrate processing apparatus that sprays a processing liquid (e.g. chemical liquid, deionized water) to semiconductor wafers, which will be called as “wafers” hereinafter, thereby to remove contaminants, for example, particles, organic contaminants, etc. from the wafers. As such a substrate processing apparatus, there is known a substrate processing apparatus that includes a rotor accommodating a plurality of wafers (e.g. twenty six wafers) at appropriate intervals. The rotor is provided with a plurality of parallel holding rods (e.g. six rods). Each of the holding rods has twenty six holding grooves formed at appropriate intervals in the longitudinal direction to hold the peripheries of twenty six wafers. By six holding rods of the rotor, each wafer is held at six positions about the periphery stably. Being retained in twenty six holding grooves of each holding rod respectively, twenty six wafers are arranged in parallel with each other at appropriate intervals in the rotor. By spraying chemical liquid etc. while rotating the wafers accommodated in the so-constructed rotor, particles etc. can be removed from the wafers uniformly.
In the conventional substrate processing apparatus, however, when accelerating or decelerating the rotation of a rotor, the rotating speed of the wafers does not follow the rotating speed of the rotor, so that a phenomenon of the wafers' slipping in the holding grooves arises. Consequently, the peripheries of the wafers are worn to produce particles. Further, the abrasion of holding grooves due to the above slipping requires a frequent exchange of the holding rods.
In order to solve the above problem, it has been supposed to employ a piece adapted to apply pressure on the periphery of a wafer by making use of a centrifugal force. However, sufficient pressure could not be produced unless the revolutions of a rotor becomes high. Noted that the above piece is formed by an elastic member, such as rubber, in view of making sure of holding the wafer. However, the elastic member does not have the property of chemical-resistance and heat-resistance enough to process the wafer with chemicals.